Header for implantable pulse generator and method of making same

ABSTRACT

A header for use in implantable pulse generator devices. The header is cart, of electrical connector assembly having one or more openings designed to receive the terminal pin of an electrical lead wire or electrode. The header is designed to provide and sustain long-term electrical and mechanical lead wire connections between the electrodes of a terminal pin and the implantable pulse generator device.

CROSS-REFERENCED TO RELATED APPLICATIONS

This application is a non-provisional application of application Ser.No. 61/329,173, filed Apr. 29, 2010 and claims priority from thatapplication which is also deemed incorporated by reference in itsentirety in this application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention, relates to implantable pulse generators and, moreparticularly, implantable pulse generator headers and components of suchheaders. The present invention also relates to methods for manufacturingheaders for implantable pulse generators.

II. Discussion of Related Art

In medical technology an implanted pulse generator (IPG) may be employedfor a variety of purposes. An IPG is a battery powered device designedto deliver electrical stimulation to the body. An IPG is typically anintegral component of a surgically implanted system, which includes theIPG, one or more leads and an external programmer. Such systems areused, for example, to provide deep brain stimulation, vagus nervestimulation, heart defibrillation, management of heart rhythms, ortreatment of other disorders.

The IPG is typically implanted within a person's body, usually beneaththe clavicle. Leads are then routed through the body between the site tobe stimulated and the IPG. The leads are then coupled to the header ofthe IPG to carry signals between the IPG and the treatment site. The IPGcan be calibrated using the external programmer by a physician (such asan electrophysiologist, neurologist or cardiologist) or by a nurse orother trained technician to meet the individual patient's needs. The IPGmust be replaced periodically upon battery depletion. Battery depletioncan occur within three to five years, though battery life is dependenton individual usage. End of battery life can be reasonably predicted bythe use of a telemetry between the IPG and the external programmingdevice. This allows the IPG to be replaced prior to battery failure.

One example of an IPG is a heart pacemaker (or artificial heartpacemaker, so as not to be confused with the heart's natural pacemaker),a medical device which uses electrical impulses to regulate the beatingof the heart. When the IPG is employed as an artificial heart pacemaker,the IPG is used in combination with a lead comprising a set ofelectrodes which carry stimulation pulses from the IPG to the heart andelectrical signals back from the heart to the IPG which senses andresponds to such signals. The primary purpose of a pacemaker is tomaintain an adequate heart rate, either because the heart's nativepacemaker is not fast enough, or because there is a block in the heart'selectrical conduction system. Modern pacemakers are externallyprogrammable and allow the electrophysiologist to select the optimumpacing modes for individual patients. Some IPG devices combine apacemaker and defibrillator in a single implantable device. Multipleelectrodes stimulating differing positions within the heart are oftenused to improve synchronization of the contractions of the upper andlower and chambers of the heart.

Another type of IPG is an implantable cardioverter-defibrillator (ICD),a small battery-powered electrical pulse generator which is implanted inpatients who are at risk of sudden death due to ventricular fibrillationor ventricular tachycardia. The device is programmed to detect cardiacarrhythmia and correct it by delivering a jolt of electricity. Incurrent variants, ICD devices have the ability to treat both atrial andventricular arrhythmias as well as the ability to perform biventricularpacing in patients with congestive heart failure or bradycardia.

The process of implantation of an ICD is similar to implantation of apacemaker. Like pacemakers, ICD devices are coupled to a set of leadscontaining electrode (s) and wire (s) which are passed though thevasculature to desired locations in the heart. For example an electrodecan be passed through a vein to the right chambers of the heart, andthen lodged in the apex of the right ventricle. Providing defibrillationpulses at this location has been found to be advantageous. As is thecase with pacemaker leads, the leads are coupled to the header of theICD and used to carry both stimulation pulses from the ICD to the heartand electrical signals from the heart to the ICD.

ICDs constantly monitor the rate and rhythm of the heart and can delivertherapies, by way of an electrical shock, when the electricalmanifestations of the heart activity exceed one or more presetthresholds. More modern devices can distinguish between ventricularfibrillation and ventricular tachycardia (VT) and may try to pace theheart faster than its intrinsic rate in the case of VT, to try to breakthe tachycardia before it progresses to ventricular fibrillation. Thisis known as fast-pacing, overdrive pacing or anti-tachycardia pacing(ATP). ATP is only effective if the underlying rhythm is ventriculartachycardia, and is never effective if the rhythm is ventricularfibrillation.

Other IPG devices served as neurostimulators used to treat pain,incontinence, and other neurologic and muscular conditions. Such IPGdevices have a header used to couple the IPG to leads containing aplurality of wires and electrodes which deliver stimulating pulses fromthe IPG to nerves and muscles to provide beneficial therapies. Theelectrodes and wires of the leads may also be used to carry electricalsignals back to the IPG.

The various types of IPG devices referenced above typically have aheader to which the leads are attached The header typically includes oneor more bores each configured to receive a terminal pin of a lead. Theterminal pin will typically contain a plurality of electrodes spacedalong its length. Likewise, the bore will typically have a matching setof electrical contacts along its length which are spaced to formelectrical connections with the electrodes of the lead pin. Theelectrical connections should be isolated from each other to prevent ashort or unintended propagation, of signals along a particular channel.The number and spacing or the electrodes and contacts may vary, butstandards have emerged related to such numbers and such spacing forvarious types of stimulation systems.

Previous header designs and manufacturing techniques have resulted indifficulty in maintaining component alignment, spacing, and isolation.Likewise, previous header designs and manufacturing techniques made itdifficult, if not impossible, to adequately test the assembly before itwas fully complete. If testing demonstrates an issue exists with theheader after manufacturing is complete, the entire header needs to bediscarded and typically none of the components can be salvaged Thus, todate there has been a real need in the art for a custom solutionallowing for interim. testing of the electrical, components of a bore ofa header and the assembly thereof before overmolding of the componentsis performed to complete the manufacture of the header. Morespecifically, there is a real need for product design and manufacturingmethods which allow conformance to be assessed prior to final part,generation, increasing assurance the product meets performancerequirements while at the same time decreasing the risk, of needing toscrap a more expensive finished product.

The inventors also believe previous devices and manufacturing methodscreate difficulty in maintaining the desired balance between mechanicaland electrical properties. Examples of deficiencies include: (1) astrong mechanical insertion force resulting in excessive pressureexerted on the inner seal and electrical components of the bore; (2)excessive electrical contact resulting in shorts or faults which candraw off potential battery power; (3) insufficient retention forcesresulting in an electrode of the bore losing position or falling out ofplace; and (4) manufacturing tolerances which create challenges relatedto meeting the electrical and mechanical conformance requirements. Thetolerances of the electrode lead wires present further challenges withrespect to the header's ability to achieve the desired electrical andmechanical responses. There exists a real and substantial need toprovide efficient and cost effective manufacturing methods and designswhich meet these challenges.

Prior art header designs often comprise various thin wire connections.Notable are those composed a of spring-type connector in the form of afemale leaf spring, canted coil spring or wire “slide by” connector. Theinventors believe these devices offer an adequate electrical connection,but are fragile in design. Such connectors can be damaged or brokeneasily upon insertion of lead pins into the bore. In addition, currentdesigns are expensive to manufacture requiring multiple component piecesand challenging assembly steps driving up cost.

Prior art header designs also provide seals which are intended toisolate the electrical channels, but are subject to failure eitherduring manufacture or as a result of the insertion or removal of leadpins. These seals can also result in alignment problems which ariseduring overmolding, typically one of the last steps in the manufacturingprocess. If during overmolding the molding pressures or temperaturesdeform the seals in an unintended manner, improper alignment of thecomponents and improper sealing can occur. To avoid such problems,thermoset rather than thermoplastic materials requiring lower moldingpressure, but longer molding cycle times have often been employed. Whilethe resulting header will work, the header is expensive and timeconsuming to manufacture. Also, whatever materials and moldingtechniques are used, great care must be taken to ensure proper alignmentand isolation increasing the level of skill and care required tomanufacture the header.

For the reasons set forth above, assembly of IPG devices is currentlyvery labor-intensive and time-consuming, and requires skilledcraftsmanship on the part of each person performing the assembly steps.In prior assembly methods, each individual component of the bore of theheader is individually placed and aligned, either by press fittingand/or fixturing, in a cavity block which is either pre-molded or yet tobe cast. Problems associated with these techniques include: electricalleakage between components, electrical failures and excessive forcerequired for inserting and withdrawing lead pins. Such manufacturingtechniques result in a high scrap rate and a high scrap cost, sincefailures are detected only after completion of whole device assembly.Furthermore the final assembly is confined to a specific outer castingdesign.

SUMMARY OF THE INVENTION

Numerous advantages are obtained when manufacturing a header for animplantable pulse generator by:

-   -   a. Forming a plurality of spring contact rings, each spring        contact ring having a bore; a plurality of ring seals, each ring        seal having a bore; a sleeve having a wall surrounding a bore;        and a strain relief having a bore;    -   b. Forming a subassembly by (a) inserting at least some of the        plurality of spring contact rings and at least some of the        plurality of ring seals into the bore of the sleeve such that        each spring contact ring is separated from any adjacent spring        contact ring by a ring seal, and (b) inserting at least a        portion of the strain relief into the bore of the sleeve to        secure the spring contact rings and ring seals in a position in        which adjacent spring contact rings and ring seals are in        contact with each other and the bores through the strain relief        and each of the spring contact rings and rings seals of the        subassembly are aligned with each other;    -   c. Inserting a molding pin through the bores of the strain        relief and each of the spring contact rings and ring seals of        the subassembly;    -   d. Overmolding the subassembly to lock the spring contact rings,        ring seals and strain relief of the subassembly in position; and    -   e. Removing the molding pin.

The method manufacture outlined above makes it possible to test thesubassembly before performing the overmolding step. Also, the step ofovermolding may be performed at a pressure or annealing temperaturewhich partially collapses the wall of the sleeve to lock the springcontact rings, ring seals and strain relief of the subassembly inposition with respect to each other and electrically isolate each of thespring contact rings of the subassembly from each other through thecooperation of the wall of the sleeve and the ring seals of thesubassembly.

Further, the sleeve can be constructed so as to include a plurality ofwindows such that there is a window adjacent to each of the springcontact rings of the subassembly. A wire can be passed through a windowand electrically coupling to the spring contact ring adjacent to thewindow to form an electrically conductive path through the sleeve.During the overmolding step, some of the material used to perform theovermolding step enters the windows to assist in locking at least, oneof the spring contact rings in position. The wire can be installedeither before or after the overmolding step. If the wire is installedafter the overmolding step, it may be advantageous to prevent theovermold material from occluding the window.

Likewise, either the strain relief or the sleeve can include aprojection with the other of the stain, relief or sleeve including achannel. The channel should have a straight section and a cammingsection angled from the straight section. The strain relief can therebybe temporarily locked to the sleeve by moving the strain relief into thebore of the sleeve until the projection reaches the camming section, andthen twisting the strain relief relative to the sleeve to cause theprojection to enter the camming section. So that the same sleeve can beused with different combinations of spring contact rings and ring seals,the camming section may angled from the straight section at an angleother than 90 degrees. Thus, when the sleeve and strain relief arerotated relative to each other, the strain relief is drawn tight againstthe collection of spring contact rings and ring seals within the sleeve.During the overmolding step, some of the material used to perform theovermolding step enters the channel to assist in locking at least thestrain relief in position.

Problems encountered in the prior art can also be alleviated byproviding unique and novel ring seals. The ring seals may be constructedto include a deformable outer wall, a deformable inner wall defining abore through the ring seal, a pair of side walls and a rigid core havingexposed portions along each of the sidewalls. The exposed portions ofthe rigid core act as stops for maintaining a predefined minimumdistance between two of the adjacent spring contact rings. Providingsuch a core offers additional advantages in that the rigid core alsoprevents the inner diameter of the ring seal from deforming during theovermolding step even as the outer diameter of the sealing ring deforms.The inner core may, for example, be made of PEEK and the other portionsof the ring seal of silicone.

Various problems are also resolved by providing unique and novel springcontact rings which include a ring and a spring having spiral, radialcut spring fingers. This arrangement provides a spring with a longerbeam deflection than those typically used while retaining a compactoverall shape. Such a spring also ensures good contact between thespring and an electrode of a lead pin. The design allows the spring tobe more robust reducing the risk that the spring will break. duringnormal use, and particularly during insertion or retraction of a leadpin. During the overmolding step, the molding pin engages a molding pin.The spring contact ring adequately resists molding pressures typicallyencountered.

The sleeve may be made of any suitable material. Examples include, butare not limited to PEEK, polyurethane and polysulfone. The thickness ofthe wall of the sleeve will depend on the material from which the sleeveis constructed and the molding pressure used during overmolding. Thematerial and molding pressure should be selected to permit the sleeve todeform to firmly lock the components of the subassembly in place. Thesleeve may also be designed to include structures on its outer surfacefor supporting at least one other component of the header. Such othercomponent could be an RE antenna, another subassembly, or any otherdesired component to be included in the header.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a spring contact ring;

FIG. 2 is an end view of the spring contact ring of FIG. 1;

FIG. 3 is an exploded view showing the components of the spring contactring of FIG. 1;

FIG. 4 is a cross-sectional view of the spring contact ring of FIG. 1;

FIG. 5 is a perspective view of a ring seal;

FIG. 6 is a perspective view of the core of the ring seal of FIG. 5;

FIG. 7 is an end view of the ring seal of FIG. 5;

FIG. 8 is a cross-sectional view of the ring seal taken through line 8-8of FIG. 7;

FIG. 9 is a cross-sectional view of the ring seal taken through line 9-9in FIG. 7;

FIG. 10 is a perspective view of a strain relief;

FIG. 11 is a side view of the strain relief of FIG. 10;

FIG. 12 is an end view of the strain relief of FIG. 10 ;

FIG. 13 is a cross-section of the strain relief through line 13-13 ofFIG. 12;

FIG. 14 is a perspective view of a tip block;

FIG. 15 is a bottom view of the tip block of FIG. 14;

FIG. 16 is a cross-sectional view of the tip block through line 16-16 ofFIG. 15;

FIG. 17 is a perspective view of a sleeve;

FIG. 18 is an end view of the sleeve of FIG. 17;

FIG. 19 is a side view of the sleeve of FIG. 17;

FIG. 20 is a cross-sectional view of the sleeve through line 20-20 inFIG. 19;

FIG. 21 is an exploded view of a subassembly;

FIG. 22 is a cross-sectional view of the sleeve of FIG. 17 showing asubassembly comprising various components coupled to the sleeve; and

FIG. 23 is a perspective view of a header.

DESCRIPTION OF PREFERRED EMBODIMENT

The following discussion is presented to enable a person skilled in theart to make and use the present teachings. Various modifications to theillustrated embodiments will be readily apparent to those skilled in theart, and the principles described herein may be applied to otherembodiments and applications without departing from the presentinvention. Thus, the present invention is not intended to be limited toembodiments shown, but is to be accorded the widest scope consistentwith the principles and features disclosed herein. The followingdetailed description is to be read with reference to the figures, inwhich like elements in different figures have like reference numerals.The figures, which are not necessarily to scale, depict selectedembodiments and are not intended, to limit the scope of the presentinvention. Skilled artisans will recognize many useful alternatives tothe teachings and the examples provided herein falling within the scopeof the invention exist and may be employed without deviating from theinvention.

Embodiments of the present invention include electrical contacts.Various types of electrical contacts may be used. By way of example,such electrical contacts may be in the form of a spring contact ringcomposed of flanged internal fingers shaped and cut in a matter tosustain long term electrical, and mechanical lead wire connections whenused in implantable pulse generator (IPG) devices. The spring contactring is designed to sustain contact between the pulse generator and anelectrode (lead. wire) of a lead pin through which electrical impulsesare transmitted to or from the body tissue. The spring contact ringmaintains mechanical force and alignment requirements with an electrodeof a lead pin when the lead pin is inserted and retained to the pulsegenerator header in order to sustain, the desired electrical connection.The spring contact ring should not be susceptible to damage by insertionor removal of the lead pin.

Typically, a header made in accordance with the present invention, willhave a number of electrical connectors aligned in a row which separatelyengage electrodes on the lead pin. It is therefore important tophysically and electrically isolate the electrical connectors from eachother to prevent current leakage or propagation of signals alongunintended electrical paths. Therefore, the electrical connectors shouldbe separated by a seal member. Maintaining proper spacing and alignmentbetween the electrical connectors is also important since eachelectrical connector of the lead is intended to be coupled to a separateelectrode of the lead pin. More specifically, the spacing of theelectrical connectors of the header must correspond to the spacing ofthe electrodes of the lead pin.

Embodiments of the present invention also include a sleeve designed tocontain various connector and seal components. This assembly is uniquein the way it incorporates a sleeve to maintain component alignmentthroughout the manufacturing process. This can allow for a lessexpensive method of manufacturing requiring less assembly time (labor)and less material usage. Tn. addition the component sleeve can bemulti-functional, as it can be employed in various overmolded headerdesigns, without the setup and redesigns required by existing methods.The manufacturing method is module based. Elements of the manufacturingmethod typically include: (1) manufacturing individual components, e.g.,connectors, seals, and sleeves; (2) creating a subassembly from suchcomponents, electrical connectors and seals; (3) testing the subassemblyto ensure conformance to manufacturing standards; and (4) over moldingthe subassembly.

Embodiments of the present invention disclose a sleeve which cooperateswith various components to keep the components in alignment. Theinventors have found it more efficient to manufacture using the sleevein combination with other components to create a subassembly which canbe tested prior to overmolding.

FIGS. 1-4 show a spring contact ring 10 of a type which may be employedwhen practicing the present invention. The spring contact ring 10includes an outer housing 12. The outer housing 12 comprises an outerwall 14 and an inner wall 16 surrounding an aperture or bore 18. Theouter wall 14 includes a recessed channel 20. The inner wall 16 includesa flange 22 and a stop surface 23.

The spring contact ring 10 also includes a spring 24. Spring 24 includesa base 26. Extending from the base 26 is a plurality of spring fingers28. Each spring finger 28 includes a flange portion 30 terminating in anelectrical contact zone 32. As best shown in FIGS. 3 and 4, the fingers28 are all cut or otherwise formed in a radial fashion to provide alonger beam deflection and, at the same time, a compact overall shape.

When the spring contact ring 10 is assembled, the base 26 of the spring24 engages the flange 22 and is either directly welded to the flange 22or sandwiched. between the flange 22 and a cap 34 which is secured tothe inner wall 16 of the housing 12 to secure the spring 24 in place.Neither the flange portion 30 nor the electrical contact zone 32 offingers 23 are permanently secured to any structure other than the base26 of the spring 24 and the fingers 28 are permitted to flex within thebore 18. When either a molding pin (not shown) or a lead pin (not shown)is inserted through bore 18 of the spring contact ring 10, the outwardmovement of the fingers 28 is constrained by the stop surface 23 of theinner wall 16 of the outer housing 12. The fingers 28 may be biasedtoward the longitudinal axis of the bore 18. In one alternativearrangement, the electrical contact zone 32 of each finger 28 is pinchedbetween a lead pin (or molding pin) and the stop surface 23 when such apin is inserted through the bore 18 to provide sold physical contactbetween the pin and the electrical contact zone 32. In anotheralternative arrangement, the pin contacts the inner wall of the housingadjacent the stop surface, but does not cause the spring fingers tocontact the stop surface. This is beneficial during overmolding becausethe mold pin supports the ring sufficiently to resist molding pressurewithout the risk of damaging the spring fingers. In any case, the stopsurface prevents over-bending of the spring fingers 28 during insertionof a lead pin or molding pin.

Electrical connector ring 10 in inexpensive to make by requiring lessmanufacturing steps as the process uses more adaptable CNC machining ormetal injection molding (MIM) methods requiring less setup, fewer partsand minimal assembly, lowing associated manufacturing costs. Materialsof construction which may be used to make spring contact ring 10include, but are not limited to, alloys of stainless steel 316L,titanium, MP35N, or nitinol.

Spring contact rings, such as spring contact ring 10, provide a strongerstructure than the coil or wire springs which may also be employed. Assuch, spring contact ring 10 is less likely to break or crack.

FIGS. 5-9 illustrate a ring seal 40 having an advantageous construction.The ring seal 40 has a core 42. The core 42 includes a ring-shaped basestructure 44. Extending outwardly from the base structure 44 is aplurality of stops 46. The core 42 is preferably made of a firstmaterial which is stiff, durable and a non-conductive plastic such asPEEK. The core 42 is overmolded with a second material which is softerand resilient such as silicone rubber. As shown, the ring seal 40 has aninner portion 48 and an outer portion 50 each made of the secondmaterial. The inner portion 48 surrounds an aperture or bore 52 and hasa pair of sealing lobes 54 and 56 extending into the bore 52. The ringseal 40 also has a first side wall 58 and a second side wall 60. Theside walls 58 and 60 are also made of the second material, but the endsof the stops 46 are left exposed when the core 42 is overmolded with thesecond material.

The ring seal 40 offers a number of advantages. The stops 46 can be usedto register and maintain proper spacing between adjacent components. Thelobes 54 and 56 engage a lead pin (or molding pin) inserted into thebore 52 to form a suitable seal. The core generally inhibits compressiveforces which may deform on the outer portion 50 from being transferredto and deforming to an unacceptable degree the inner portion 43.Likewise, the core inhibits forces causing deformation of the innerportion. 48 from deforming the outer portion 50 to any unacceptabledegree.

FIGS. 10-13 show a strain relief. The strain relief 60 comprises acylindrical wall 62 surrounding a central passage or bore 63. Extendingoutwardly from the cylindrical wall 62 is a pair of locking projections64. The central passage is shown as including shoulder 66 at one end anda hexagonal interior surface 68 at the other. Alternative shapes may beused in lieu of a hexagonal. shape without deviating from the invention.The two ends 70 and 72 are open to the central passage or bore 63.

FIGS. 14-16 show a set screw block 80. The set screw block 80 (alsoreferred to as a tip block) has an outer wall 82 with a pair ofalignment, channels 83 and 84. The interior of the set screw block 80includes a pin-receiving channel or bore 86 extending through the block80 in a direction generally perpendicular to the alignment channels 83and 84. The set screw block 80 also includes a threaded set screwchannel 88 which extends generally perpendicularly from channel 86 andreceives a set screw (not shown) which is used to lock in place a pin(not shown) inserted into the pin-receiving channel. While a set screwblock 80 has been shown and described, other locking mechanismarrangements are known which may alternatively be employed to lock thepin in place.

FIGS. 17-20 show an electrical connector sleeve 90. The electricalconnector sleeve 90 comprises a generally cylindrical outer wall 92surrounding a central. bore 94. One end 96 of the sleeve 90 includes ashoulder 98 and a pair of fingers 100 and 102. Spaced along the lengthof the cylindrical outer wall 92 is a plurality of windows. Three suchwindows 104, 106 and 108 are shown. These windows extend through theouter wall 92. Extending inwardly from end 110 of the outer wail 92 is apair of strain relief locking channels 112 and 114. The strain relieflocking channels 112 and 114 each include a straight section 11.6extending inwardly from end 110 and a camming section 118 projecting atan angle from the straight section 116. As best shown in FIG. 20, thisangle can be greater than 90° for reasons explained below.

To provide an electrical path between each individual spring contactring 10 eventually located within the sleeve and the exterior of thesleeve 90, one end of an electrical conductor (not shown) may be passedthrough one of the windows 104, 106 or 108 adjacent to the springcontact ring 10 and coupled to the spring contact ring 10. The recesschannel 20 of the spring contact ring 10 may be employed, to create acoupling between the end of the electrical conductor and the springcontact ring 10.

Sleeve 90 can be composed of various rigid materials, encompassing: (1)either amorphous or semi-crystalline polymers within the categoriesdefined as engineering, high performance or ultra polymers, includingpoly-ethyl-ethyl-ketone, polysulfone, polyurethane, polyphenylene,polyimides, liquid crystal, polycarbonate, polyamide, ABS, COC, oralloys thereof; (2) ceramics, or; (3) metallic materials such as of Si316L, MP35N and titanium. Certain advantages are achieved by forming thesleeve 90 of a material such as PEEK, polyurethane or polysulfone of asuitable thickness which will allow the sleeve to compress when exposedto overmolding pressures or annealing temperatures to lock componentswithin the sleeve 90 in place.

FIGS. 21 and 22 illustrate how a subassembly 122 can be created using asleeve 90, three spring contact rings 10, four ring seals 40, a setscrew block 80, and a strain relief 60. The set screw block 30 iscoupled to the sleeve 90 by inserting the fingers 100 and 102 of thesleeve 90 into the alignment channels 83 and 84 of the set screw block80. Other mechanisms for coupling the set screw block 80 to the sleeve90 may be employed without deviating from the invention. The set screwblock 80 is then slid along the fingers 100 and 102 until thepin-receiving channel 86 of the set screw block 80 is aligned with thebore 94 of he sleeve 90. Friction. between the fingers 100 and 102 andthe alignment channels 83 and 84 is typically sufficient to temporarilyretain the set screw block 80 in place as manufacturing of thesubassembly continues. The set screw block 80 is permanently held inplace by the overmold material which ultimately encapsulates thesubassembly 122.

Next, ring seals 40 and spring contact rings 10 are inserted inalternating fashion into the bore 94 of the sleeve 90. Finally, a strainrelief 60 is inserted and locked in place. Locking of the strain relief60 to the sleeve 90 is achieved by inserting the end 70 of the strainrelief into the bore 94 of the sleeve 90 through end 110, aligning theprojections 64 of the strain relief 60 with the straight sections 116 ofthe locking channels 112 and 114 of the sleeve 90, continuing to advancethe strain relief 60 into the bore 94 until the projections 64 reach thecamming sections 118 of the locking channels 112 and 114 and thenturning the strain relief 60 relative to the sleeve 90 so that theprojections 64 enter the camming sections 118. As the sleeve and strainrelief are turned relative to each other, cooperation between theprojections and walls of the camming section 118 cause the strain reliefto be locked in place and because of the angle of the camming sections,drawn toward the arrangement of seals and spring contact rings. As shownin FIG. 22, a ring seal 40 resides between the set screw block 80 andthe adjacent spring contact ring 10. Likewise, a ring seal 40 residesbetween the strain relief 60 and the adjacent spring contact ring 10.Alternatively, a seal could be built into either the set screw block 80or the strain relief 60.

Once the subassembly shown in FIGS. 21-22 is complete, various tests maybe performed to ensure the quality of the subassembly. If a part is notperforming to specifications at this stage, it is still possible todisassemble the subassembly, replace any defective parts or otherwisemake repairs.

After such testing is completed and the results analyzed, a molding pin(not shown) can be inserted through the pin-receiving channel of thesubassembly formed by alignment of the bores of the strain relief 50,seals 40, spring contact rings 10 and setscrew block 80. The molding pinwill prevent the overmold material from entering the pin receivingchannel during the overmolding process. Known techniques for overmoldingcan then be employed to complete the header.

One advantage of overmolding is that it serves to lock in position thevarious components of the subassembly 122. This is particularly true ifthe overmolding is performed by injection molding at a. pressure whichwill compress or collapse the sleeve 90 without crushing the sleeve 90.The collapsed sleeve 90 will also cooperate with the ring seals 40 toelectrically isolate the spring contact rings 10 from each other andfrom the strain relief 60 and the set screw block 80. As the wall of thesleeve 90 collapses, the outer walls of the sealing rings 40 deformwhile the inner walls of the sealing rings substantially maintain. theirshape.

Pressures which will suitably compress or collapse the sleeve 90 withoutcrushing the sleeve 90 will depend on the material from which the sleeve90 is made and the thickness of the sleeve 90. By way of example andwithout limitation, a sleeve 90 made of PEEK having a thickness of0.035-0.045 inches will not compress adequately if the mold pressure isbelow about 16000 pounds per square inch (psi) and will crush if themold pressure is above about 25000 psi. Therefore, if sleeve 90 is madeof PEEK and has a thickness of 0.035-0.045 inches, the molding pressureshould be in the range of about 16000 psi to about 25000 psi if,however, the sleeve 90 has the same thickness, but is made of 40%glass-filled PEEK, a molding pressure in excess of 25000 psi will berequired to adequately compress the sleeve to adequately lock thecomponents of the subassembly 122 in place. After the overmolding stepis completed, the header 120 is removed from the mold and the moldingpin is removed exposing the bore in which a lead terminal pin may beinserted to form electrical connections between the wires of the leadand the spring contact rings 10 of the header 120.

Other techniques may also be used to lock the components of thesubassembly in place. For example, the header casing 124 and thesubassembly 122 may be exposed to an annealing temperature whichpartially collapses the wall of the sleeve 90 to lock the spring contactrings 10, ring seals 40, strain relief 60 and the set screw block 80 inplace, e.g., in a position in which (a) adjacent spring contact rings 10and ring seals 40 are in contact with each other and the bores throughthe strain relief 60, each of the spring contact rings 10 and ring seals40, and the set screw block 80 are aligned with each other; and (b) thewall of the sleeve 90 and ring seals 40 cooperate to electricallyisolate each of the spring contact rings 10 from each other and thespring contact rings 10 from the set screw block 80 and the strainrelief 60. Alternatively, only the subassembly 122 might be subjected tothe annealing temperature. This could be done before overmolding orbefore inserting the subassembly into a bore of a preformed headercasing 124. When the header casing 124 is formed by overmolding thesubassembly 122, the overmold material will mechanically secure theheader casing 124 to the subassembly 122. When the header casing 124 ispreformed. with a bore 126, some means (e.g., a suitable adhesive ormechanical structure) should be employed to lock the subassembly 122 inplace within the bore 126 of the header casing 124.

FIG. 23 shows a completed header 120. If the overmold material 124 is aclear material, the sleeve of the subassembly 122 will be visible asshown in FIG. 23. During overmolding, the in allows the entrance to thepin-receiving channel 126 to remain open.

Strain relief 60 can be composed of various rigid materials,encompassing: (1) either amorphous or semi-crystalline polymers withinthe categories defined as engineering, high performance or ultrapolymers, including poly-ethyl-ethyl-ketone, polysulfone, polyurethane,polyphenylene, polyimides, liquid, crystal, polycarbonate, polyamide,ABS, COC, or alloys thereof; (2) ceramics and its alloys (3) metallicalloys of SS 316L, MP35N and titanium.; however, the present inventionis not limited to these materials.

Set screw block 80 can be made using more adaptable CNC machining ormetal injection molding (MIM) methods, requiring less setup, fewer partsand minimal assembly, lowering associated manufacturing costs. Materialsof construction used within the art of making block 80 are alloys ofstainless steel 316L, titanium and MP35N.

Connector seals 40 can be made using more adaptable injection moldingmethods, requiring less setup, fewer parts and minimal assembly,lowering associated manufacturing costs. Materials of construction usedwithin the art of making connector seal 40 are liquid silicone used toovermold a stiff substrate made of a non-conductive material such asPEEK. Examples of other materials suitable for use include: (1) eitheramorphous or semi-crystalline polymers within the categories defined asengineering, high performance or ultra. polymers, includingpoly-ethyl-ethyl-ketone, polysulfone, polyurethane, polyphenylene,polyimides, liquid crystal, polycarbonate, polyamide, ABS, COC, oralloys thereof; (2) ceramics and its alloys; (3) metallic alloy of SS316L, MP35N and titanium.

Thus, embodiments of the ELECTRICAL CONNECTOR SLEEVE are disclosed. Oneskilled in the art will appreciate the present teachings can bepracticed with embodiments other than those disclosed. The disclosedembodiments are presented for purposes of illustration and notlimitation, and the present teachings are limited only by the followingclaims.

1. A method of manufacturing a header for an implantable pulse generatorcomprising: a. forming a plurality of spring contact rings, each springcontact ring having a bore; a plurality of ring seals, each ring sealhaving a bore; a sleeve having a wall surrounding a bore; and a strainrelief having a bore; b. forming a subassembly by (a) inserting at leastsome of the plurality of spring contact rings and at least some of theplurality of ring seals into the bore of the sleeve such that eachspring contact ring is separated from any adjacent spring contact ringby a ring seal, and (b) inserting at least a portion of the strain.relief into the bore of the sleeve to secure the spring contact ringsand ring seals in a position in which adjacent spring contact rings andring seals are in contact with each other and the bores through thestrain relief and each of the spring contact rings and rings seals ofthe subassembly are aligned with each other; c. inserting a molding pinthrough the bores of the strain relief and each of the spring contactrings and ring seals of the subassembly; d. overmolding the subassemblyto lock the spring contact rings, ring seals and strain relief of thesubassembly in position; and e. removing the molding pin.
 2. The methodof claim 1 further including the step of testing the subassembly beforeperforming the overmolding step.
 3. The method of claim 1 wherein thestep of overmolding is performed at a pressure which partially collapsesthe wall of the sleeve to thereby lock the spring contact rings, ringseals and strain relief of the subassembly in position with respect toeach other and electrically isolate each of the spring contact rings ofthe subassembly from each other through the cooperation. of the wall ofthe sleeve and the ring seals of the subassembly.
 4. The method of claim1 wherein the sleeve further comprises a plurality of windows, eachwindow adjacent to one of the spring contact rings of the subassembly,and the method further includes passing at least one wire through awindow and electrically coupling the at least one wire to the springcontact ring adjacent to the window.
 5. The method of claim 4 wherein,during the overmolding step, some of the material used to perform theovermolding step enters a window to assist in locking at least one ofthe spring contact rings in position.
 6. The method of claim 1 whereinthe step of inserting at least a portion of the strain relief into thebore of the sleeve includes aligning a projection with a channel, saidchannel having a straight section and a camming section angled from thestraight section, (b) moving the strain relief into the bore of thesleeve until the projection reaches the camming section, and (c)twisting the strain relief relative to the sleeve to cause theprojection to enter the camming section.
 7. The method of claim 6wherein the camming section is angled from the straight section at anangle other than 90 degrees.
 8. The method of claim 6 wherein, duringthe overmolding step, some of the material used to perform. the overmolding step enters the channel to assist in locking at least the strainrelief in position.
 9. The method of claim 1 wherein the step of forminga plurality of ring seals includes forming at least one ring seal so itincludes a rigid core having exposed portions which act as a stop formaintaining a predefined minimum distance between two of the adjacentspring contact rings.
 10. The method of claim 9 wherein the rigid corealso prevents the inner diameter of the ring seal from deforming duringthe overmolding step even as the outer diameter of the sealing ringdeforms.
 11. The method of claim 10 wherein said rigid core is made ofPEEK and other portions of the ring seals are made of silicone.
 12. Themethod of claim 1 wherein at least one of the spring contact ringsincludes a ring and a spring having spiral, radial coo spring fingers.13. The method of claim 1 wherein the sleeve is formed to includestructures on its outer surface for supporting at least one othercomponent of the header.
 14. The method of claim 1 wherein such othercomponent is a tip block.
 15. The method of claim 13 wherein such othercomponent is an RF antenna.
 16. The method of claim 13 wherein suchother component is another subassembly.
 17. The method of claim 1wherein the strain relief includes a seal for electrically isolating thestrain relief from the spring contact rings of the subassembly.
 18. Amethod of manufacturing a header for an implantable pulse generatorcomprising: a. forming a plurality of spring contact rings, each springcontact ring having a bore; a sleeve having a wall surrounding a bore;and a strain relief having a bore; b. forming a plurality of ring seals,each ring seal having a deformable outer wall, a deformable inner walldefining a bore through the ring seal, a pair of side walls, and a rigidcore having exposed portions along each of the sidewalls; c. forming asubassembly by (a) inserting at least some of the plurality of springcontact rings and at least some of the plurality of ring seals into thebore of the sleeve such that each spring contact ring is separated fromany adjacent spring contact ring by at least one ring seal and a minimumdistance is maintained between adjacent spring contact rings by therigid core of at least one ring seal, and (b) inserting at least aportion of the strain relief into the bore to secure the spring contactrings and ring seals in a position in which adjacent spring contactrings and ring seals are in contact with each other and the boresthrough the strain relief and each of the spring contact rings and ringsseals of the subassembly are aligned with each other; d. inserting amolding pin through the bores of the strain relief and each of thespring contact rings and ring seals of the subassembly; e. overmoldingthe subassembly to lock the spring contact rings, ring seals and strainrelief of the subassembly in position; and f. removing the molding pin.19. The method of claim 18 wherein the step of overmolding is performedat a pressure which partially collapses the wall of the sleeve anddeforms the outer walls of the sealing rings while the inner walls ofthe sealing rings substantially maintain their shapes to thereby lockthe spring contact rings, ring seals and strain relief of thesubassembly in position with respect to each other and electricallyisolate the spring contact rings of the subassembly from each otherthrough the cooperation of the wall, of the sleeve and the ring seals ofthe subassembly.
 20. A method of manufacturing a header for animplantable pulse generator comprising: a. forming a plurality of ringseals, each ring seals having a bore; a sleeve having a wall,surrounding a bore; and a strain relief having a bore; b. forming aplurality of spring contact rings, each spring contact rings having anouter ring and a spring having spiral, radial cut spring fingers; c.forming a subassembly by (a) inserting at least some of the plurality ofspring contact rings and at least some of the plurality of ring sealsinto the bore of the sleeve such that each spring contact ring isseparated from any adjacent spring contact ring by at least one ringseal, and (b) inserting at least a portion of the strain relief into thebore to secure the spring contact rings and ring seals in a position inwhich adjacent spring contact rings and ring seals are in contact witheach other and the bores through the strain relief and each of thespring contact rings and rings seals of the subassembly are aligned witheach other; d. inserting a molding pin through the bores of the strainrelief and each of the spring contact rings and ring seals of tinesubassembly; e. overmolding the subassembly to lock the spring contactrings, ring seals and strain relief of the subassembly in position; andf. removing the molding pin.
 21. A method of manufacturing a header foran implantable pulse generator comprising: a. forming a plurality ofspring contact rings, each spring contact ring having a bore; aplurality of ring seals, each ring seal having a bore; a sleeve having awall surrounding a bore; and a strain relief having a bore; b. forming asubassembly by (a) inserting at least some of the plurality of springcontact rings and at least some of the plurality of ring seals into thebore of the sleeve such that each spring contact ring is separated fromany adjacent spring contact ring by a ring seal, and (b) inserting atleast a portion of the strain relief into the bore of the sleeve tosecure the spring contact rings and ring seals in a position in whichadjacent spring contact rings and ring seals are in contact with eachother and the bores through the strain relief and each of the springcontact rings and rings seals of the subassembly are aligned with eachother; c. forming a header casing having a bore sized to receive thesubassembly, d. inserting the subassembly into the bore of the headercasing; and e. exposing the header casing and subassembly to anannealing temperature which partially collapses the wall of the sleeveto thereby lock the spring contact rings, ring seals and strain reliefof the subassembly in position with respect to each other andelectrically isolate each of the spring contact rings of the subassemblyfrom each other through the cooperation of the wall of the sleeve andthe ring seals of the subassembly.
 22. A method of manufacturing aheader for an implantable pulse generator comprising: a. forming aplurality of spring contact rings, each spring contact ring having abore; a plurality of ring seals, each ring seal having a bore; and astrain relief having a bore; b. forming a header casing having a bore;c. forming a subassembly by (a) inserting at least some of the pluralityof spring contact rings and at least some of the plurality of ring sealsinto the bore of the header casing such that each spring contact ring isseparated from any adjacent spring contact ring by a ring seal, and (b)inserting at least a portion of the strain relief into the bore of theheader casing to secure the spring contact rings and ring seals in aposition in which adjacent spring contact rings and ring seals are incontact with each other and the bores through the strain relief and eachof the spring contact rings and rings seals of the subassembly arealigned with each other; d. inserting the subassembly into the bore ofthe header casing and locking the subassembly in place.
 23. The methodof claim 22 wherein the strain relief includes a seal for electricallyisolating the strain relief from the spring contact rings of thesubassembly.
 24. A spring contact ring comprising: a. an outer ringcomprising a wall surrounding a bore, the inside surface of the borehaving a flange and an stop surface, and b. a spring comprising a baseengaging the flange and a plurality of a spiral, radial cut springfingers, each of the fingers haying a and electrical contact zone andfree to flex within area of the bore between the longitudinal axis ofthe bore and the stop surface as a pin is inserted into the bore.
 25. Aseal having a center bore comprising: a. a rigid, core made of a firstmaterial, and including a ring-shaped base and a plurality of stops,having exposed portions, extending outwardly from the base, b. a cover,made of a second material softer than the first material, whichencapsulates portions of the rigid core other than the exposed portionsof the stops, the cover having an inner portion and an outer portion,wherein the core inhibits compressive forces deforming one of theportions from substantially deforming the other of the portions.
 26. Asleeve comprising: a. a cylindrical wall having first and second endsand surrounding a bore, the wall having a plurality of windows, b. aplurality of locking channels extending inwardly from the first end ofthe wall, each of the locking channels including a straight sectionextending from the first end of the wall toward the second end and acamming section projecting at an angle from the straight section. 27.The sleeve of claim 26 wherein the angle is greater than 90 degrees. 28.The sleeve of claim 26 wherein the sleeve further includes a shoulderand a pair of fingers at the second end used to couple the sleeve to alocking mechanism.